1. Field of the Invention
This invention relates to the preparation of 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo[5.5.0.0.sup.5,9 0.sup.3,11 ]dodecane. More specifically, the present invention relates to improved processes for synthesizing the stated compound.
2. Technology Background
4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo[5.5.0.0.sup.5,9 0.sup.3,11 ]dodecane has been prepared by a procedure reported by Joseph H. Boyer and colleagues in Heterocycles, vol. 31, no. 3, pp. 479-480 (1990). According to the reported procedure, 1,4-diformyl-2,3,5,6-tetrahydroxypiperazine (1) in trimeric glyoxal (dihydrate) was added to concentrated sulfuric acid at 0.degree. C. and stirred at 10.degree. C. to 15.degree. C. for 5 hours. The reaction mixture was cooled to 0.degree. C., and 100% nitric acid was added dropwise. Stirring was resumed for 2 hours at 0.degree. to 10.degree. C. and then for 45 hours at 25.degree. C. The mixture was poured onto ice, and a colorless solid precipitated. It was isolated and washed to give a mixture which contains some 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazatetracyclo[5.5.0.0.sup.5,9 0.sup.3,11 ]dodecane (2) (herein referred to as TEX). The reaction is shown below: ##STR1## There are several disadvantages of the reported procedure for manufacturing TEX. For instance, the applicants have found that the reported procedure produces very impure TEX in low yields such that the described process is not capable of producing large quantities of TEX. The applicants have also found that glyoxal trimer is not necessary to produce TEX. Moreover, the reported procedure is very time-consuming, requiring over two days (approximately 52 hours) to complete. Finally, the reported procedure requires special reactants, such as pure nitric acid (100%), which are difficult to obtain and highly unstable.
It will be appreciated that there is a need in the art for alternative processes of manufacturing TEX which are efficient, produce TEX in high yield, and do not require the long processing time reported in the prior art (52 hours). It would also be an important advancement to provide processes for manufacturing TEX which utilize readily available reactants.
Such processes for manufacturing TEX are disclosed and claimed herein.